CMP Slurry Composition for Cobalt Corrosion and Low-k Protection
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Solution Overview
Problem
Current chemical mechanical polishing (CMP) slurries are inadequate for polishing cobalt-containing surfaces in semiconductor fabrication, leading to cobalt corrosion, uneven topography, and inadequate material removal rates, which hinders the advancement of chip miniaturization and performance.
Innovation Solution
A CMP composition comprising an abrasive, pH adjuster, barrier film removal rate enhancer, low-k removal rate inhibitors, azole-containing corrosion inhibitor, and cobalt corrosion inhibitor, designed to minimize cobalt loss and defects while effectively removing barrier films and dielectric materials, ensuring smooth topography and controlled material removal rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional polishing compositions containing cerium oxide and/or aluminum oxide are used, then polishing capability is achieved, but metal surface discoloration and mottling occur due to iron particle contamination
Solution Approach 1:
The patent converts the harmful effect of iron particle contamination by introducing oxidizing agents that transform iron particles into non-contaminating oxidized forms. The composition includes hydrogen peroxide, persulfates, and/or percarbonates as oxidizing agents that chemically treat iron particles generated during polishing, preventing them from causing discoloration and mottling on the metal surface while maintaining effective polishing action.
Solution Approach 2:
The patent changes the chemical parameters of the polishing composition by incorporating specific oxidizing agents (hydrogen peroxide, persulfates, percarbonates) alongside traditional abrasives. This parameter change transforms the chemical environment during polishing, enabling iron particles to be oxidized in situ and preventing their harmful effects without compromising the mechanical polishing action of the abrasives.
2Productivity
If iron-containing abrasives are used for polishing, then polishing action is effective, but iron particles contaminate the metal surface causing discoloration
Solution Approach 1:
The patent applies oxidizing agents that convert harmful iron particles into beneficial oxidized forms during the polishing process. The hydrogen peroxide, persulfates, and/or percarbonates chemically react with iron particles generated from abrasive wear, transforming them into non-contaminating species that do not cause discoloration or mottling, thereby maintaining both effective polishing action and high surface finish quality.
Solution Approach 2:
The oxidizing agents act as intermediary substances that mediate between the iron-containing abrasives and the metal surface. These intermediaries (oxidizing agents) capture and neutralize iron particles before they can contaminate the surface, allowing the use of effective iron-containing abrasives while preventing the harmful contamination effects.
3Device complexity
If conventional polishing compositions are used, then polishing process is simple, but multiple polishing steps are required to achieve desired finish
Solution Approach 1:
The patent merges multiple functions into a single polishing composition: mechanical abrasion from cerium oxide and/or aluminum oxide, chemical oxidation of iron particles from hydrogen peroxide/persulfates/percarbonates, and prevention of contamination. This combination allows one polishing step to simultaneously achieve material removal, surface finishing, and contamination prevention, eliminating the need for multiple sequential polishing steps.
Solution Approach 2:
The polishing composition is designed with multi-functionality, serving as both an abrasive medium for material removal and a chemical treatment medium for iron particle oxidation. This universal composition performs multiple tasks that traditionally required separate processes, including polishing, iron particle removal, and surface protection, thereby reducing the total number of steps required.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The composition effectively suppresses low-k removal rates, reduces cobalt liner loss, and minimizes defects on copper surfaces, achieving suitable material removal rates for cobalt, copper, and barrier materials, thereby improving semiconductor substrate smoothness and performance.
Implementation Method 1
The composition comprises an abrasive, a surfactant, and an oxidizing agent selected from hydrogen peroxide, persulfates, and percarbonates. The oxidizing agent converts iron particles into non-contaminating oxidized iron particles, preventing discoloration and mottling on the metal surface.
Data Source
AI summary
A polishing composition includes an abrasive; a pH adjuster; a barrier film removal rate enhancer; a first low-k removal rate inhibitor; a second low-k removal rate inhibitor; an azole-containing corrosion inhibitor; and a cobalt corrosion inhibitor. This disclosure also relates to a method of polishing a substrate that comprises cobalt using the polishing compositions described herein.